Meningococcal disease remains a major cause of morbidity and mortality throughout the world. The presently available capsular polysaccharide vaccines are poorly immunogenic in infants at highest risk for developing the disease. Efforts to overcome the neonatal unresponsiveness to these T- independent polysaccharide antigens include the specific triggering of anti polysaccharide antibodies in a use of anti idiotypic antibodies. We have employed this technique in combination with hybridoma technology to produce a monoclonal anti idiotypic antibody which mimics the capsular polysaccharide of N. meningitidis group C. We propose to clone and sequence the variable light and variable heavy chains of the gene encoding the idiotypic and anti idiotypic antibodies. On the basis of the amino acid sequence a three dimensional computer model will be generated. The computer model will allow us to predict important immunogenic determinants. Ultimately our goal is to generate synthetic peptides to these immunogenic determinants and to test these peptides for the ability to elicit an anti polysaccharide antibody response in animals. We will characterize the nature of the immune response triggered by both anti idiotypic antibody and the corresponding synthetic peptides. Synthetic peptide vaccines might offer several advantages over the conventional polysaccharide vaccines: 1) They may act as T dependent antigens and elicit an effective immune response in infants. 2) Production would be inexpensive and affordable for underdeveloped nations. 3) Synthetic peptides should be stable antigens not requiring refrigeration. 4) This methodology may be applicable for numerous infectious agents for which no effective vaccine exists, e.g., N. meningitidis group B.